Tools located in very deep wells frequently need pressure levels for setting that can be beyond the capabilities of surface pumping equipment. One way to set such tools is to develop a boost force in the form of a pressure surge to get the internal pressure in the tool to a level where the tool can be set.
One attempt at doing this is illustrated in U.S. Pat. No. 7,870,895 where initial movement of the packer setting mechanism triggers either a chemical reaction that generates gas pressure or a setting off of explosive to get a pressure surge to set the packer. These two sources can be an assist or the sole driving force for setting the packer with a pressure sensitive piston. Generating the pressure surge with chemicals or explosives creates increased cost as well as safety issues and transportation issues to the well site.
What is needed is a simpler and cheaper way to generate a pressure surge to set a subterranean tool and the present invention addresses this issue. The kinetic energy of flowing well fluids are deployed and a hammer effect is created by abrupt interruption of circulating fluid while still leaving a flow channel open to reach an actuating piston for the tool. The fluid hammer effect that is created provides sufficient pressure to set the tool. The hammer effect is created with either a rapid increase in flow to close a circulation port or a dropped object on a seat that isolates a circulation port while leaving access open to an actuation piston for the tool. In the preferred embodiment the tool is a pressure set packer but other types of tools are contemplated. Those skilled in the art will more readily appreciate the details of the invention from the attached description and the associated drawings while recognizing that the full scope of the invention is to be found from the appended claims.